advertisement

Dbms

50 %
50 %
advertisement
Information about Dbms
Business & Mgmt

Published on March 15, 2014

Author: TejKiran2

Source: slideshare.net

advertisement



  Problems with file processing systems  Inconsistent data  Inflexibility  Limited data sharing  Poor enforcement of standards  Excessive program maintenance

 Character :The most basic logical element is character.Which consists of alphabetic, numeric or other symbol. Field : It consists of grouping of characters.For example, the grouping of alphabetic characters.For example grouping of alphabetic characters in a person’s name form a name field. Record :Related fields of data are grouped to form a record. File :A group of related records is a data file, or table. Database :The highest level in the hierarchy is the database.A database is an integrated collection of logically related records or files. Levels of Data

  Controlled Redundancy  Ease of learning and use  Data independence  Accuracy and Integrity  Privacy and security  Shared  Recovery from failure  Performance Objectives of Data Base

  Operational Data Base  Analytical Data Base  Data Warehouse Data Base  Distributed Data Base  End User Data Base  External Data Base Types of Data Bases

  Data Bases store detailed data needed to support operations of entire organization  They are also called Subject Area Databases ,transaction database and production database  A customer database, inventory database, and other database containing data generated by business operations Operational Database

  Databases store data extracted from selected operational and external databases  Consists of data mostly needed by an organization’s managers and other end users  They are also called management databases or information databases  They are the databases accessed by the online analytical processing (OLAP) systems, decision support systems and executive information systems Analytical Database

  Stores data from current and previous years that has been extracted from various operational and analytical databases of an organization  It is a central source of data that has been standardized and integrated so it can be used by managers and other end user professionals throughout an organization Data Warehouse Databases

  Databases of local work groups and departments at regional offices, branch offices, manufacturing plants and other work sites  Can include segments of common operational and common user databases as well as data generated and used only at a user’s own site  Ensuring that all the data in distributed databases are consistently and concurrently updated Distributed Database

  These databases consist of a variety of data files developed by end users at their workstations  For example, users may have their own electronic copies of documents they generated with word processing packages or received by electronic mail. End User Database

  Access to external online databases or data banks is available for a fee from commercial information services , or for free of price from many sources on the internet  For example, data are available in the form of statistics on economic and demographic activity from statistical data banks  Abstracts from newspapers, magazines, and other periodicals from bibliographic data banks External Database

 DBMS is the software that permits an organization to centralize data, manage them efficiently, and provide access to the stored data by application programs . DBMS acts as an interface between the application program and the physical data files DBMS has three components  A data definition language  A data manipulation language  A data dictionary Database Management System

  The data definition language is the formal language used by the programmers to specify the content and structure of database  It defines each data element as it appears in the database before that data element is translated into the forms required by application programs Data Definition Language

  This language contains commands that permits end users and programmers to extract data from the database to satisfy information requests and develop applications  The most prominent data manipulation language today is structured query language (SQL) Data Manipulation Language

  This is an automated or manual file that stores definitions of data elements and data characteristics such as usage, physical representation, ownership, authorization and security  Many data dictionaries can produce lists and reports of data utilization, groupings, program location and so on Data Dictionary

  Organizes data  Integrates data  Separates data  Controls data  Retrieves data  Protects data Functions of DBMS

  Reduced programming costs  Reduced development and implementation time  Reduced program and file maintenance costs  Reduced data Redundancy  Increase flexibility Benefits of DBMS

 Data is not stored in a random fashion. It is organized for efficient retrieval.  Sequential organization  Indexed Sequential Organization  Inverted List Organization  Direct Access Organization Data Storage and Retrieval

  It simply means storing and sorting in physical, contiguous blocks within files on tape or disk  Records are also in sequence within each block  It is best suited in reading one record after another without a search delay  The records can be added only at the end of the file Sequential Organization

  Data is stored in physically contiguous blocks and uses indexes to locate records  Indexed Sequential Organization reduces the magnitude of the sequential search and provides quick access for sequential and direct processing  The drawback is the extra storage space required for the index. It also takes long to search the index for data access or retrieval Indexed Sequential Organization

  It differ from the previous in the index level and record storage  The indexed sequential method has a multiple index for a given key, whereas the inverted list method has a single index for each key type  In inverted list records are not needed to be stored in a particular sequence. They are placed in data storage area but indexes are updated for the record keys and location  Inverted lists are best for applications that request specific data on multiple keys Inverted List Organization

  In direct access file organization, records are placed randomly throughout the file  New records are added at the end of the file or inserted in specific locations based on software commands  Records are accessed by addresses that specify their disk locations. An address is required for locating a record, for linking records , or for establishing relationships Direct Access Organization

 Hierarchical Data Model Employee Job assignments BenefitsCompensation Performance Salary hist Pension Life insurance Health

 Network Data Model Course 2Course 1 Course 3 Student 1 Student 2 Student 3 Student 4 Student 5 Student 6

 Relational Data Model Dept .no D nam e D loc Em p no Dep. A Dep. B Dep. C Emp . no E name E title E sal Dep. no E1 D A E2 D A E3 D B E4 D B E5 D C E6 D A

  The schemes (schema) define categories of data and their properties .  External Schema or user schema is the user’s view of a part of the database  Conceptual Schema is the overall logical view of the database  Internal Schema or data storage definition is the way the data is physically organized in storage Data Schemes

 External Schemas General Model User View User View User View Conceptual Schema Internal Schema Stored Database

  Each user of the database (an application program or a person formulating a query ) is concerned with only a small portion of the database  Each user is interested in only a part of the entities in the database, only part of the attributes of those entities, and certain relationships among the entities  External schema consists basically of definitions of each of the various external record types in the external view  The external schema is written using the DDL portion of the user’s data sub language External Schema

  The conceptual schema is the logical view of the entire database . It represents as closely as possible the real entities and their relationships .  It contains integrity rules and authorization rules, but it does not contain information about how the data items are stored Conceptual Schema

  The internal schema or physical data model describes how the database is organized for physical storage and access  The internal schema includes information on ordering of records, block sizes, storage indexes, use of pointers and access strategies being used Internal Schema

  A mapping is a transaction of one schema to another  In order for a user to access data, the user view of the data as reflected in the external schema must be translated into the overall conceptual schema  In the same way, the conceptual/internal mapping translates logical descriptions of data in the conceptual schema to physical locations and access paths in the internal scheme Mapping

 Mapping between Schemas External view External view External view External schema1 External schema 2 External schema 3 Overall conceptual view Conceptual schema Internal schema (DDL) Stored Database

Add a comment

Related presentations

Canvas Prints at Affordable Prices make you smile.Visit http://www.shopcanvasprint...

30 Días en Bici en Gijón organiza un recorrido por los comercios históricos de la ...

Con el fin de conocer mejor el rol que juega internet en el proceso de compra en E...

With three established projects across the country and seven more in the pipeline,...

Retailing is not a rocket science, neither it's walk-in-the-park. In this presenta...

What is research??

What is research??

April 2, 2014

Explanatory definitions of research in depth...

Related pages

Datenbank – Wikipedia

Das Datenbanksystem ist das ausgeführte DBMS zusammen mit den zu verwaltenden Daten der Datenbank. Ein DBS gewährleistet die persistente Speicherung ...
Read more

Was ist Datenbank-Management-System (DBMS)? - Definition ...

Ein Datenbank-Management-System (DBMS) ist ein Programm, über das ein oder mehrere Anwender Daten in eine Datenbank einstellen und abrufen können.
Read more

Datenbank-Systeme / DBMS: Grundbegriffe und Konzepte

Grundbegriffe und Konzepte von Datenbank-Systemen In diesem Abschnitt werden die folgenden Konzepte thematisiert: Der Unterschied zwischen einer Datenbank ...
Read more

DBMS :: database management system ...

Datenbankmanagementsysteme (DBMS) werden für die Informationsverwaltung eingesetzt. Ein solches System besteht aus den Daten und den Programmen mit ...
Read more

Oracle (Datenbanksystem) – Wikipedia

SQL Workbench/J: The free DBMS-independent SQL Tool; QueryAdvisor: The tool for advanced GUI based tracefile and wait interface analysis.
Read more

DBMS – Alles aus einer Hand.

Über uns. Innovation aus Tradition - Das Know-how von DBM.S resultiert aus einer über 60-jährigen Arbeit in der DIY-Branche. Aus diesen Wurzeln stellt ...
Read more

Database Management System (DBMS) - Definition

« Start | 10 Gründe | Versionen | Beispiele | Download | Kaufen | Kontakt | Impressum » Was ist ein Database Management System ? Das Database Management ...
Read more

Job-Verwaltung mit dem Oracle Scheduler

Datenbank-Jobs in der Datenbank zu verwalten, ist schon seit jeher mit dem Package DBMS_JOB in der Datenbank möglich. Mit Oracle Database 10g ist nun das ...
Read more

Database - Wikipedia

A database is an organized collection of data. It is the collection of schemas, tables, queries, reports, views, and other objects. The data are typically ...
Read more

100 DBMS_SQL - Oracle

107/206 100 DBMS_SQL. The DBMS_SQL package provides an interface to use dynamic SQL to parse any data manipulation language (DML) or data definition ...
Read more